Serum fluoride concentrations, biochemical and histopathological changes associated with prolonged sevoflurane anaesthesia in horses.

This study investigates the effects of prolonged exposure to the anaesthetic sevoflurane in horses, and if this leads to damage in liver and kidneys. The study finds that there are minimal changes in renal function and morphology but no substantial damage to the liver.

Research Overview

The research sought to understand the impact of the anaesthetic sevoflurane, which decomposes into fluoride and a vinyl ether (labelled Compound A), on the health of horses’ kidneys and livers. The study included six thoroughbred horses which were given an extended 18 hours of low-flow sevoflurane anaesthesia.

Monitoring and Investigations

• Several physiological and clinical tests were conducted both during and before anaesthesia on the horses to monitor their health.
• Levels of fluoride in the serum were recorded, given that the anaesthetic breaks down into this compound.
• Additionally, the hepatic and renal function of these animals was assessed through laboratory tests.
• Furthermore, kidney and liver samples were taken before and after the experiment for microscopic examination.

Findings

• All monitored cardiopulmonary parameters remained within clinically acceptable ranges.
• After anaesthesia was started, levels of fluoride in the serum began increasing, until they stabilised after eight hours, remaining between 38 and 45 micromol.
• The analysis of serums showed slight increases in glucose and creatinine kinase levels, and a decrease in total calcium.
• After ten hours of anaesthesia, faint time-related changes were observed in urine, including burgeoning volume, glucosuria and enzymuria.
• The kidney showed minor microscopic changes, primarily occurring in the distal tubule, though no significant alterations were detected in liver tissue.

Conclusions

The results of this research highlight that horses can undergo unusually lengthy sevoflurane anaesthesia with minimal risk to hepatic health. The changes in renal function and morphology following sevoflurane inhalation were minimal and judged to be clinically irrelevant. These could have been induced by the duration of the anaesthesia, physiological stressors, sevoflurane or its by-products or even other unknown factors related to the specific animals or experimental conditions.